A blade ring of a turbine is supported by a support device provided at the lower half of a casing. The thickness of an adjustment member, such as a shim or liner, of the support device is adjusted to adjust the vertical position of the blade ring and thus to adjust a gap between a rotor and the blade ring. Patent Document 1 discloses a support device including a support attached to the lower half of a blade ring, a lower half liner supporting the support, and an upper half liner holding down the support. The vertical position of the blade ring is adjusted by adjusting the thickness of the lower half liner. The upper half liner holding down the support prevents the blade ring from being lifted up in releasing the casing.